The invention relates to a connection element and a method for producing a connection element.
A generic type of connection element in the form of a setting bolt for connecting at least two metal sheets is known from DE 10 2006 002 238 A1. The connection element shown there comprises a tapered region and a shaft region, among other things. The whole connection element can thus be coated. Alternatively, it is also possible that the connection element is formed as two parts, wherein the tapered region and the shaft region can be constructed from different materials.
It is necessary when connecting high-strength materials that the tapered region is formed to be particularly hard, since otherwise the tapered region is plastically deformed when the connection element drives through the materials. Curing the whole connection element can thus rectify this, wherein this is only possible up to a certain limit, since the susceptibility to hydrogen embrittlement increases with an increasing yield strength. Furthermore, a continuous coating of the connection element usually only provides a compromise of a relatively low friction when penetrating into the metal sheets to be connected and a still adequate holding force or strength of the joining connection because of a still adequate friction in the shaft region. This is particularly important when metal sheets with a relatively low stiffness are to be joined to one another.
Thus, the object of the present invention is to provide a connection element and a method for producing a connection element, by means of which metal sheets with a high yield strength or metal sheets with a low stiffness can be joined particularly well.
The connection element according to the invention, in particular a setting bolt, to connect at least two components, in particular metal sheet components, comprises a tapered region and a shaft region, the properties of which are different. The connection element according to the invention is thus characterised in that the connection element is formed as one piece.
In contrast to the connection element known from DE 10 2006 002 238 A1, which is produced from two parts of different hardness, that have then been connected to each other, in the connection element according to the invention, it is thus provided that the connection element is formed as one piece or one part. A complex joining of the connection element during the production thereof can thus be avoided.
Preferably, the tapered region has a higher strength than the shaft region. For example, the tapered region can have a strength of at least 2,000 MPa, wherein the shaft region has a strength of less than 1,500 MPa. In other words, the connection element can have locally specific different properties in terms of its material properties. The tapered region can, as a result of it being able to be formed to be very hard, penetrate in particular ultra high-strength steels, such as Usibor, for example, without plastic deformation of the tapered region. However, because the shaft region has a lower strength than the tapered region, this is soft enough to ensure that it is not susceptible to hydrogen embrittlement. Alternatively, it would however also be conceivable that the connection element is produced from two different materials, wherein the tapered region and the shaft region are each produced from different materials in order to obtain the corresponding material properties. Thus, the shaft region and a head region can be produced from the same material.
Preferably, the tapered region alternatively or additionally has a sliding coating and the shaft region has an adhesive coating. As a result, the tapered region can have a relatively low friction value and can penetrate into a material with a lower stiffness, in particular, particularly easily. Because of the adhesive coating of the shaft region, it has a relatively high friction value and thus ensures a high holding force of the produced joining connection.
In a further advantageous embodiment of the invention it is provided that the tapered region has a lower surface roughness than the shaft region. In other words, when connecting two metal sheets by means of the connection element on the tapered region, there is thus relatively low friction, wherein the shaft region, in comparison to the tapered region, is formed to be very rough, whereby a particularly high holding force of the joining connection produced by means of the connection element can be obtained.
In the method according to the invention for producing a connection element, in particular a setting bolt, to connect at least two components, in particular metal sheet components, a tapered region and a shaft region of the connection element are produced having different properties. The method according to the invention is thus characterized in that the connection element is produced to be one piece. Advantageous embodiments of the connection element according to the invention can thus be seen as advantageous embodiments of the method according to the invention for producing the connection element.
In one advantageous embodiment of the method according to the invention, it is provided that the tapered region is laser cured or cured inductively. Preferably, the tempered region is also still tempered after the laser curing or inductive curing. In other words, it can be provided that, during production of the connection element, it is tempered in the tapered region, whereby the tapered region can be produced with a higher strength than the shaft region.
Finally, it is provided according to a further advantageous embodiment of the method according to the invention that the whole connection element is provided with an adhesive coating, then only in the tapered region, the adhesive coating is removed in a first immersion bath and then the tapered region is provided with a sliding coating in a second immersion bath. As a result, the tapered region can be provided with a sliding coating during production of the connection element in a particularly simple manner and the shaft region can be provided with an adhesive coating during production of the connection element.
Further advantages, features and details of the invention result from the description of preferred exemplary embodiments below, as well as by means of the drawing. The features and feature combinations referred to in the description as well as the features and feature combinations referred to below in the description of the figures and/or shown solely in the figures can be used not only in each specified combination but also in other combinations or alone without leaving the scope of the invention.